Catalyst for methanol manufacture and method of producing same



Patented May I6, 1933 UNITED STATES PATENT O BARNETT I. nonon,

OF CHICAGO, ILLINOIS, A CORP on NEW HAVEN, coNN'EorIcUr; ASSIGNOR TO s. KARPEN & sacs, oRAr oNor'wEs'r VIRGINIA CATALYST FbR' IMIE'IHANQI-v MANUFACTURE AND METHQD OF PRODUCING SAME g No Drawing.

This invention relates to the production of synthetic methanolby the reaction ofoxides of carbon with hydrogen at elevated temperatures and pressures, and to an improved catalytic agent which is particularlywell reaction between hydrogen and oxides of carbon; also, to .the method of producing such proved catalyst which may be usefully emmethanol.

The use of contact bodies, serving as catalysts, is well known in the. art of effecting reaction drogen to produce, for example, methanol; and many catalysts of this nature have been disclosed in patents and literature pertainlng to the subject. Some of the known catalysts produce only moderately good results; and many-of the disclosed catalysts possess, from a practical standpoint, very little value n the art. a I

The precise manner in which these catalysts act to aid in reaction between carbon oxides and hydrogen is not known. It has been found advantageous, however, to employ mixtures of materialsof different compositions in a finely divided state; and experience has shown that the physical condition of the materials in the mixture is a most important factor, as is also the composition of the materials employed. On the other hand, the precise nature of the physical condition of any selected materials may be incapable ofbeing clearly set forth. In such cases, resort to a description of the method of preparation is necessary. I The present invention is based on the discovery that it is possible toprepare mixtures of zinc oxide and copper in such a state or condition that a highly eifective'contac't body is afforded; and thatsuch contact body can be very advantageously employed to cause reaction between carbon oxides and hydrogen;

suited to the purpose of aiding and expediting the ployed .in the economical manufacture of between carbon oxides and hy- Application filed January 1-6, 1930. Serial No. 421,263.

and particularly in the production of methanol, or methyl alcohol; a a

Following is a description of the preferred method of producing a catalyst andemploying it in the production of methanol: j

ive parts by weight of zinc and'one part by weight of copper (or their chemical equiv alents) are converted into nitrates and dissolved in sufficient water to produce a'solu tion whose concentration is approximately 15 grams of the total metal per liter. This solution is then treated at room temperature or higher with a saturated solution of sodium carbonate to effect the simultaneous precipitation of the zinc and copper carbonates, intimately commingled. The precipitate is Washed to remove nitrates, filtered, pressed in a hydraulic press, dried and broken up into granules of any desired size. To produce the final catalyst, preferably these granules are treated with hydrogen, carbon monoxide, or mixtures of them, at atmospheric pressure and at tern eratures ranging from 100 C. to 450. referably, this treatment is carried out by heating at 150 C. for a time, and ultimately raising the temperature to'300, Q. The time of treatment may extend over ape riod of several hours, a period of 8 to 12 hours having been found very satisfactory.

The effect of thetreatment probably is to decompose the carbonates, or reduce them to oxides, and reduce the copper oxide to metallic copper, which is thus present in the mixture in the form ofyery fine particles dispersed throughout the zinc oxide. The zinc oxide possesses as a result of the treatment, a physical structure which is well adapted to the purpose of the catalyst. The particles of copper, as a'result of the treatment, possess a deep purple, or dark reddish purple color, which apparently is characteristic of a very active condition of the copper for catalysis purposes. Copper produced by the method described does notdeterio ate if exposed to air. The improved catalystis placed in'a suitable reaction chamber and the gases to'be' united are passed throughthe catalyst at a suitable speed and pressure, while the retort or chamber is maintained at a suitable temperature. The ranges of speed, temperature part of carbon monoxide by v. Ata temperature of 250 Gi about ofthe carbgn morifixide is conzmderted to mathano' I under e con 'tions jpst usinga space velocity of approximately 10,000; At a space velocity of approximately 1% this catalg gives'a dime-yield. (S. T. Y.) of a g: of methang; per 24 per cu. 0 ca eymg a perature of about: 250C. anthm pounds per sq. in. pressure. Using other fi res, when the im roved catalyst is pie in .a. copper line steel bomb andrexposed to a gas composed substantially of two; arts b volume of hydrogen and one oficar n oxhimta pressure of 2600 unds per: sq. in. and a temperature of 300 with: gas flowing at a space veloclt of 31,700 (volumes of gas measured at stan ard conditions; entering per hour per volume of catalyst). the catalyst' converted about 33.7% of that} to methanol and gave a S. T. Y. of. 105* gallons per 24 hours, per cubic foot of? catalyst space.

The composition can be varied within quite wide limits. It seems quite im rtant, however to employ a large excess 0 zinc. Prefera the ratio of zinc to copper (atom c proportions) is at least four to one, but this may be reduced to. two to one, or even lower,

but with less satisfactory results- The initial compounds of the improved catalyst are produced by precipitation of the compounds rom solutions of the metals for two reasons. One is to msure unty; and another is to insure the desired cm of the I catalyst which follows from precipitation from a solution of the soluble salts followed by reducing treatment, which leaves the materials in' the desired form. The joint precipi tation, while important from the standpoint of easy production of an intimatel commingled mixture perhaps is not an a lute essential. On the other hand, the-feature of placin the materials used in the condition described above is highly important.

The precise method of precipitating from the solution the materials composing the catalyst is important; Thus, the best re; sults are obtained by employing an alkali metal carbonate for precipitating the zmc and co er compounds.

owever, a reasonably active catalyst may be obtained by precipitating from the nimay p0 proximately two of hydrgm to one ratio.

. noose trate solution of zinc andcopper mentioned above zinc and copper compounds b means of a hydroxide of an elemental al metal, sodium or potasium. Thus h droxide may be em oyed for effecting the preci itation and eresulting compounds washed, dried and granulated and. then subjected to reducin treatment in the manner stated above to o in the catalyst; and this catalyst after reducing treatment mabe employed in the synthesis of methanol in e manner stated' above'. Using a catalyst obtained in this manner, placed in. a copperlined steel bomb and exposed to a gas-roomprising two arts by volume of hydrogen and one of C at 31111158811 of 2600 Pmmdb per sq. in. at a temperature oa0o C a gas flowing at atshpace velocity;of.'25,000,.aboufi 13 r cent of. e (30 -is..conuerted to metin ano in one pass, and aspace-time-yield of 313 gallons 0 per cubic foot of catalystspaee is obtained.

It is also possible to ammonium hydroxide to precipitate the metals from. the; solution: of solub e.- salts .buta decidedly less active catalyst resultsltap. are, therefore, thatv given the metals whi'c associated together are capable ofrproducin a methanol. catalyst, very much. neverth ess depends upon the exact mode of treatment in producin the catalyst to. the best results.

i'le it is preferred to efl'ect the precipitatron from a solution of. the mixed nitrates, it is: possible to use other soluble salts in. the solutmn. It is important, however, to avoid the. presence of impurities or contaminatin substances which may have a deleterious of feet. Thus, it is. desirable to avoid the presence of sulphur, the halides, etc. The img rl-loved catalysts described are halide-free.

e are slmply and cheaply produced and are ighly resistant in the sense that they are well adapted to retain for a long period of time, the proper qualities to serve as a' catalysti in the production of methanol, for ex-, am e. j e. foregoing detailed description has,

n given for clearness of understandin only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the rior art.

It may be added that t e activity of the catalyst may be increased by lessening the atomic per cent of zinc and correspondmgly increasing that of copper. Thus 4 to 1, 3 to 1, 2 toil an 1 to 1 ratios give larger yields at lower ogerating temperatures than a 5 to 1 copper percentage the shorter the life or stability of the catalyst. Thus, the desirability of a high zinc atomic per cent is indicated,

methanol pentwenty four hours.

n the other hand, the higher the V I. The method of producin a stable highly active copper zinc oxide cata ystwhich comprises re ucing copper carbonatev admixed with zinc carbonate in the roportion of at 6 least two atoms of zinc and one of copper, in a heated reducing gas, whereby a stable highly active catalyst comprising zinc oxide and a stable purplish free copper is produced.

,2. The method as set forth in claim 1 in which the zinc is taken in the proportion of atleast four atoms to one of copper.

' 3. The method as set forth 111 claim 1 in which the carbonates are freshly prepared 4. A stable highly active copper zinc oxide catalyst comprislng zinc oxide and purplish free copper in the proportion of at least two atoms 0 zinc to one atom of copper.

5. A catalyst as set forth in claim 4 in which there are at least four atoms of zinc to each atom of copper.

' 6. A catalyst as set forth in claim 4 in which the catalyst is of the form resulting from the reduction of zinc and copper carbonates ina heated reduc irng g as.

I BARNE DODGE. 

